There is an ongoing trend in the electronics industry to reduce or miniaturize the size of electronic components, to increase the density of components on a given printed circuit board by reducing the pitch or spacing between components, and to increase the speed or frequency at which the components operate. On large, and/or fast, and/or high-density boards the test industry has adopted the use of a printed circuit board (translator board) to connect the probes of a test fixture to the tester interface. The use of a translator board provides numerous electrical advantages over using discrete wires installed by hand wiring (wire wrapping).
In conventional wireless test assemblies, a double headed probe is used to electrically connect the translator board with the unit under test. The double headed probe is generally comprised of two parts, a probe and a probe socket. The probe is configured to be at least partially received within the probe socket, and the assembly has a spring-loaded head at each end. In operation, one spring-loaded head is electrically engaged with a test point on the unit under test (UUT) and the other spring-loaded head is electrically engaged with a test point on the translator board.
While the use of double headed probes in combination with translator boards presents certain advantages over the use of wire wrapping, there are also numerous disadvantages. One such disadvantage relates to the cost of double ended socket probes. Double headed probes are significantly more expensive than single-headed probes. The cost differential between single headed probes and double headed probes becomes significant as the number of probes increases. Notably, the number of probes required to test a complex circuit may easily number in the thousands or even tens of thousands. Thus, a significant cost savings could be realized by using single headed probes in place of double headed probes.
Another disadvantage relates to the cost of manufacturing the translator board. Printed circuit boards such as the translator board are expensive when manufactured in small quantities. There is a substantial non-reoccurring engineering (NRE) cost for designing a translator board. This NRE cost is only economical when amortized over a large number of circuits tested using the translator board.
As the complexity of the circuit being tested increases, the number of test points increases and the size of the translator board used to provide electrical connection between test machine and the test points increases. There is an inverse relationship between the size of the printed board and the number of vendors capable of manufacturing the board. Thus, as the physical size of the translator board increases, the number of companies capable of manufacturing these boards decreases. As a result, board manufacturers charge a premium for large printed circuit boards.
The high manufacturing cost and the NRE cost makes it highly desirable to maximize the life of a translator board, which is measured in terms of test cycles. However, the life of the translator board is often diminished as a result of transient forces. The transient forces are physical forces which occur cyclically (transiently) each time a unit is tested.
Conventional wireless test assemblies impart a cyclical or transient force to the translator board each time a unit is tested. Over time this transient force causes wearing of contact pads and warping of the translator board, thereby reducing the life of the translator board.
Accordingly, a need exists for a test assembly which facilitates reliable electrical contact between a testing assembly and UUT, does not require fixed wiring, and minimizes the occurrence of transient forces on the translator board.
A need further exists for a test assembly which provides enhanced flexibility without requiring the use of double-ended probes.